Molded doors are assembled using two door facings, often molded from a wood fiber/resin compound. The door facings form the outer surfaces of the door. Such doors often include an internal frame that provides structural support. The frame typically includes stiles and rails located around the perimeter of the door. The door may also include a core material, such as expandable cardboard material, particleboard, medium density fiberboard, or other some other one-piece core component.
Manual assembly of molded doors is relatively labor intensive, expensive, and subject to quality variations. A door facing is manually placed on a production table with its intended, exteriorly disposed surface face down. The parts of a frame, comprising individual stiles and rails, are then passed through a roll coater by hand. The roll coater applies conventional glue to opposing sides of the frame parts. The coated frame parts are then placed on top of the door facing that is on the table. A second door facing is then placed on the frame parts. The resulting assembly is then indexed downwardly so that another door may be assembled. The assembly must be carefully moved, given the components can easily shift at this point.
Manual assembly of the next molded door is repeated as described above, with each successive assembly being stacked on top of the previous assembly until a predetermined quantity of door assemblies has been stacked on the table. The table of door assemblies is then transported to a press, and the stack is placed in the press. The press applies pressure to the entire stack for a period of time sufficient to allow the glue to sufficiently bond the door assemblies. Conventional glues may take about one hour or more in-press before the door reaches “green” strength. A door achieves green strength when the glue has reached sufficient bonding strength to hold the door components together for further handling. Once green strength is achieved, the doors may be removed from the press and moved to an in-process inventory until the glue reaches maximum cure strength. Depending on the glue used, the doors may need to remain in inventory for a relatively long period of time, for example four hours or more, or even twenty-four hours or more, before the glue reaches maximum bonding strength. After maximum bonding strength is achieved, the doors are moved to a final processing station. Final processing includes edge trimming the doors to customer specification and coating and/or painting the door skins and exposed edges of the stiles and rails around each door perimeter. Therefore, manufacturing time for a door using conventional methods may be twenty-four hours or more, from the time production is initiated to the resulting finished door.
Various attempts have been made to automate production of interior molded doors. However, the production equipment necessary is often very expensive, and the methods used overly complex. Production capability from a single manufacturing facility is often limited. In addition, the glues used typically require curing presses, which are relatively expensive. Furthermore, such glues require a relatively long period of time before green strength is achieved, as well as a relatively long period of time before maximum cure strength is achieved, which is impractical in an automated production system.
As such, conventional systems and methods for automated door assembly have not proven to be cost efficient. Therefore, there is a need for an automated door assembly system and method that is cost efficient, and that achieves final product quality that is desirable to consumers.